Controller Design of Power Quality-Improving Appliances

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Controller Designof Power Quality-Improving
Appliances
D. J. Hammerstrom, N. Zhou, and N. Lu Pacific
Northwest National Laboratory 902 Battelle Blvd.,
P. O. Box 999 Richland, WA 99352
USA Donald.Hammerstrom_at_pnl.gov [phone]
PNNL-SA-55816
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Let one load improve the power quality and power
factor for an entire premise
Power Quality-Improving Appliances
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Premise current before PQI
PQI appliances are like filters, but they can
only consume energy. Where the energy can be put
to good use, the PQI is, in theory, 100
efficient.
IPremise
V
IPremise
PQI current
Sum of premise and PQI currents
IPremisePQI
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Measure and Improve Current at Premise Service
Panel
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Controller Input Signals
Note PQI controller design can be greatly
simplified by using an inexpensive power factor
control chip.

• Gain
• Rectified ac voltage
• Rectified premise current

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A Simple, Nearly Failsafe Power Circuit
Most circuit failure modes would result in
normal, rated appliance conduction.
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Floating Driver Circuits

• Optically coupled PWM signal
• Adjustable positive and negative drive bias
• Same circuit works for both power switches
• Same PWM signal sent to both switches

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Prototype Hardware
Test Stand and Load
Driver and Power Circuits
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Same Premise IRMS PQI Load is Active Only When
Needed
PQI Appliance Inactive
PQI Appliance Active
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Effect of PQI Gain Input
Too High
Active
Too Low
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Effect of PQI Load Impedance
High Z Low PQI Load
Low Z High PQI Load
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Conclusions

• PQI appliances are an undiscovered opportunity
• Simple effective circuit designs
• Comparable to, but less expensive than, filters
• Improve premise power quality and power factor
  while performing useful tasks like heating water
• Theoretically high effective efficiency